Concentric shell hot-air heater



Feb. 2, i949. s. .1. HEIMAN CONCENTRIC SHELL HOT-AIR HEATER Fletl FiledApril 11, 1945 Patented Feb. 22, 1949 UNITED STATES TENT OFFICE 1 Claim.

will be directed and guided in a predetermined path from intake todischarge, absorbing a maximum of heat from its contact with the heatedparts of the combustion chamber, with high efi'lciency.

Another object of my invention is to so construct a device of the kindaforesaid, that said air will be guided in a plurality of consecutivelyreversed directions while contacting the initially heated surfaces ofth-e structure during such travel, and thence be discharged as the room-2-'- heating medium.

An added object of this invention is to construct a heater of the kinddescribed, wherein the combustion. chamber will consist of adoublewalled shell, with the inner wall being reentrant and dependingfrom the top of the chamber to a point above the bottom of the outerwall, said inner wall having its bottom sealed, and said shells closedacross their upper ends, together with means to direct the ow of air insuccessively reversed directions to engage substantially the fullsurface exteriorly of the combustion chamber.

Further objects of this invention are to so construct a heater of thekind described, that :i1

there will be a maximum of radiation surface in contact with the aircirculated therethrough, and within a very small cubic amount of heaterbody, and wherein the hottest part of the flame in the combustionchamber will be substantially at the sealed bottom of the reentrantinner shell of the combustion. chamber.

A still further object of this invention is to so yconstruct a heater'of the kind aforesaid, that the greatest advantage is had from theradiation space of the same, by transferring said heat directly from thepoints where it exists in the radiation surface of the heater, bypassing a current of air over the same to thereby become heated,

prior to discharging said air into the room to be heated.

An additional object of my invention is to provide a heater constructionwherein there will be little tendency of overheating or burning out ofthe walls of the combustion chamber, inasmuch 2 as the heat is extractedtherefrom rapidly, evenly and continuously, by a current of air passedin contact with the heated surfaces of the heater.

Other objects of this invention are to so construct a heater ofthe kinddescribed, that will be simple and easy to make and use, not likely toget out of ord-er, will keep clean over long periods of time, willeliminate indirect heating surfaces in favor of direct or radiantheating surfaces, wherein there will be a fairly direct iiow ofcombustion gases from their generation t0 their discharge, will operatewith comparatively low drafts and thereby enhance the safety ofoperation inasmuch as the said gases travel substantially continuouslyupwardly to and through the flue.

Many other objects and advantages of the construction herein shown anddescribed will be obvious to those skilled in the art to which thisinvention appertains, as will be apparent from the disclosures hereingiven.

To this end, my invention consists in the novel arrangement,construction and combination of parts and the uses mentioned, as will bemore clearly pointed out in the following specifications.

In the drawings, wherein like ref-erence characters represent like orcorresponding parts throughout the views,

Figure 1 is a substantially horizontal crosssectional view taken throughthe structure; and

Figure 2 is substantially a Vertical cross-sectional view taken throughthe same.

Referring more particularly to the drawings, wherein I have illustrateda preferred embodiment of my invention with as few parts as possible, inorder to show the invention more clearly, there is shown a space heatergenerally, with its combustion chamber I formed between a pair ofradially spaced inner and outer shells or walls 2 and 3, respectively,said inner wall being reentrant or depending into the outer shell,somewhat as shown. l

A top Wall c is provided across the space between the tops of the pairof cooperating shells i and Sto form the top end closure thereat, andthe bottom end of the inner shell 2 is provided with a transverse wall 5to seal thereacross.

Any suitable source of heat, as for instance the pot of an oil burnerl,may be interposed within the combustion chamber, below the sealed bottomof the inner shell of the said chamber, and a flue 'l may be provided tolead outwardly from the upper end of said chamber in the usual manner.In order to slow down the flow of combustion gases upwardly of thechamber, a transverse baille 8 may be positioned between said pair ofshells forming said chamber, preferably adjacent the upper end of thechamber, this baille sealing off passage of said gases of combustion,except at a point preferably remote lfrom said ue. Although said gasesmove constantly up to the flue, they move somewhat slower than withoutsucha baleandlthis, ow'or gases'rnakes for safety inoperation with a lowdraft'.

An innermostJ shell or wall 9 extends vertically from its open lower endI to a point spaced.'

above the top wall 4 of the combustion. chamber and is spaced radiallyfrom the adjacent surface of the shell member 2 to provide arrair'passage'.- way between said shells in a manner about to bedescribed.

An outermost shell or tube l I encloses-rthe outer periphery of theshell member 3 to provide an air passage between the: two, and a toprclosure l2 i bridges across the tops ofthe members 9 and l! to seal thesame against other than the predetermined path of travel of air asindicated by the arrows, said. top wallA element l2A being spaced Vabovethe top wall of. the. combustion chamber.

Openings i3 may be providedthrough. the. lower end of theoutermost shellwall H, for discharge oi"A heated airtherethrough into the room or otherspace to-be heated, and in that case, an air intake chamber I4` is=yformed above the top wall I2, by placement of a wall l5v spaced abovethe wall. I2'` toV form said intake' chamber together with, saidIlast-mentioned wall IZ, the inlet ports beingvindicatedfat I6.

.will become heated, with the greatest degree of heat being. adjacentthe bottom. wall 5, and the gases of combustion will travel. upwardlycontinuously andpastr the baie. and. outwardly Ythrough the liuc, theair entrained in: the plenum chamber will:V be. propelled. downwardlythrough the innermost.- shell. wall S- to strike the said wall 5.-,andireverse its vertical direction. and travel-up iwardlyfbetweenthe.opposed surfaces-of the shells 2. andY 9.- tothe top-of1 said.combustion chamber,

where it travels radially outwardly and then. in a? verticaldirection.vreversed from. its. last reversal, downwardly inthe-space between theshell walls 3: and Il., atfthe. lower. endof. said. spacebeinggdschargedoutwardly into.the. room or spa-ce taba he ated,throughtheoutlets. i3..

Thus-'it is seen that there.is.a-very.- lor-lgM Hath ofi travel. of. ainin.. contacawiththe. .radiation surfaces. of. theheater,r said. airbeing, out.A ocom- -iminicatilzvn with thef gases or; combustionhowever, and;that substantially all.. of. the wall surface oithacombustion chamber is. thus wiped by said; entrained air, to. obtaina direct transfer- A enceoheat to the latter and'get the` greatestadvantage ofjsnch radiation surface.

Indirect heating surfaces are. thus avoided, in

- Lavor. of. the, director. radiating heatingsurfaces of..the.combustion chamber. There is a. moving face of the combustion chamber.

, body-of.' air. irncircul'ation. with allor the Wallsur- Of course itis to be understood that the natural flow of air through the path justdescribed, may be employed, where it is desired to discharge the heatedair through the ports I=6 and use the openings IS as inlets, and inwhich case the fan may either be dispensed with or its air-propellingd1- rection reversed, the air still traveling in a series ofconsecutively reversed directions and in close contact` withathecombustion chamber wall surfaces. during. such movement.l A

Although the combustion chamber is hottest adjacent the bottom of thereentrant shell, there is. little or no danger of the same burning outthereat, inasmuchas substantially the coldest air contacts with saidhottest region to immediately absorb the radiated heat of the latter.

In ordery togetl an even more eflicient transfer of. heat from thecombustion chamber wall, a sheet of good heat-conducting material, as ofmetal for example, may be interposed to extend vertically in the spacebetween. the walls 2' and 9) and preferably. made sinuous or corrugatedias at. 41B, said sheet being, either integral'. with said wall or.welded' or otherwise well bonded theretdso as to act as an extension ofsaid radiating surface, this element I8` preferably terminating somewhatabove the open bottom of the wall 9, so that there is no undueinterference with the upward reversal of the air after' ithas; made itsdownward movement' through the' last-mentioned shell 9; The element |8thus multiplies the effective radiation surface of. the wall' 2 and moreefliciently transfers its heat' Ito the air passing along either side.of the corrugations..

A covering or insulating wall I9 may -be used to enclose the entireAstructure; and in. order to avoiding building up of. un'desirablyY highwall temperatures, vents 20 may be provided leading from the exteriorinto the space between said covering and the shell l l.

It may be. stressed. here, that the inner or reentrantA shellv wall of'the combustion chamber terminates at the sealed bottom 5 at the :heightof the hottest zone of the flameV from the pot or burner` 6, or othersource'- of'l combustion. Hence, thereA is an almost immediatetransferrence of heat. from. the zone of'. maximumv temperature withinthecombustion chamber, to the shell elements 6 and 2, and; from the'latter portions of the. shell insert to the air circulated ashereinbefore shown and described, thereby resulting in maximumefficiency of heat transferrence from said hottest part of the furnace..

A heater constructed as herein described will be exceptionally safe inits operation, inasmuch as it will work eiciently under-fairly lowdrafts, and the ow of the combustion gaseswill be progressively andconstantly upwardly tothelevel of the flue.

Having. thus. describedv my inyention, itis. obvious that variousimmaterialgmodications may be made. in the. sama without. departing fromthe spiritofmy invention; hence Ii do not wish to be understood. aslimiting myself to the. exact form, arrangement, construction andcombination of parts herein shown and described, except as limited bythe state of the art', to. which this invention appertains, and. theclaim hereunto appended.

What I' claim as new and desire to secure by Letters Patent is:

In a heater construction for discharging heated air. into a room at'substantially oor level, concentrically spacedupright inner and outer,walls,

a closure across the tops of said walls, and a closure across the bottomof said inner upright wall to thereby provide a combustion chamberenclosed by said upright walls and top and bottom closures, a pair ofshells concentrically positioned relative to said upright walls, one ofsaid shells being exteriorly of and spaced from said outer upright walland the other shell being interiorly of the inner uprightwall, saidlast-mentioned shell vhaving an open lower end terminating above saidbottom closure, said outer shell having a cold air inlet thereinto, andthe space within said outer upright wall havin-g a hot air outlettherefrom, means for entraining air from said one shell downwardly intosaid inner shell so that the same will travel in reversed directions insequence along the inner and outer side of the innermost shell and in adirection then reversed from the last-mentioned of said reverseddirections along the outer Wall of said outer upright wall, and anupright heat-conducting corrugated element arranged between saidinnermost shell and the adjacent Wall surface of the inner of theupright Walls and carried by the latter and entirely spaced from theinnermost shell and having passages through which said air is guidedthere- 6 past, said corrugated element engaging only said adjacent wallentirely above the bottom of the innermost shell toconduct heat directlyto the air flowing in contact therewith.

. SIDNEY J. HEIMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

